1. Field of the Invention
The present invention relates to a robot system that controls a robot including multiple mechanical units such as a link unit and a driving unit for driving the link unit, the mechanical units, and a robot control device.
2. Description of the Related Art
Generally, industrial robots used at manufacturing sites are articulated type robots. To facilitate replacement in the event of a failure or during maintenance, such an articulated type robot includes multiple mechanical units such as a link unit (arm unit) and a driving unit for driving the link unit.
Moreover, a safety fence at a manufacturing site serves as a partition between a robot workspace and a human workspace. This prevents a person from accidentally touching a robot. By using a teach pendant connected to a robot control device, a robot is taught to operate, for example, a robot arm unit along a desired path of movement without being deviated out of the safety fence.
However, at some manufacturing sites, a workspace cannot be divided into a robot workspace and a human workspace or productivity may be considerably reduced by dividing a workspace. Such a manufacturing site requires a practical robot system that eliminates the need for a safety fence.
Thus, a virtual area for limiting the motion of a robot (Hereinafter, referred to as a motion limiting area) is preset in the related art. A robot entering the set virtual area for limiting a motion is controlled to stop. A motion program for the control of the robot is created by teaching the robot. If the configuration of the robot is changed by replacing mechanical units such as a link unit and a driving unit, a robot motion program stored in a robot control device needs to be changed. To automatically change programs, Japanese Patent No. 3910134 discloses a technique in which a memory is provided in a replaceable mechanical unit to store a parameter for robot trajectory control.
In order to stop a robot entering the virtual motion limiting area, a 3D model of the robot needs to be created and interference between the 3D model and the virtual motion limiting area needs to be confirmed during teaching to the robot. However, Japanese Patent No. 3910134 does not describe required storage of a 3D model of a robot.
Thus, a robot control device disclosed in Japanese Patent No. 3910134 cannot confirm whether or not a 3D model of a robot interferes with a virtual motion limiting area if the configuration of the robot is changed by replacing a mechanical unit. In order to confirm interference, a 3D model of the robot needs to be manually set for the robot control device and needs to be manually changed in the replacement of the mechanical unit of the robot.
Moreover, in response to the replacement of the mechanical unit of the robot, the robot control device disclosed in Japanese Patent No. 3910134 cannot automatically change a parameter for estimating a coasting distance when the robot is stopped.